When producing micro-electronic, micro-optical and micro-mechanical components, structures are transferred to a substrate by means of a mask or a punch by using embossing or imprint lithography. If the angle between the plane of the mask and the plane of the substrate changes, the structures are no longer uniformly imprinted in the substrate. This situation is referred to as wedge error. Therefore, wedge error compensation substantially determines the quality of the imprint.
In principle, there are two kinds of wedge error compensation, namely passive wedge error compensation and active wedge error compensation.
In passive wedge error compensation, the wedge error compensating head moves with or without the substrate against the mask or punch. It contacts the mask either with its entire surface or via spacers. After the movable part of the wedge error compensating head or the substrate has contacted the mask, the relative position of the mask and the movable part of the wedge error compensating head is locked by applying brakes. The angle formed between the plane of the mask and the plane of the substrate or the surface of the movable part of the wedge error compensating head is maintained for at least one process cycle.
A problem related with passive wedge error compensation is that the brakes can hold a relatively small force of about 100 N only. For SUSS MicroTec Microlens Imprint Lithography (SMILE™), Substrate Conformal Imprint Lithography (SCIL) and Nanoimprint Lithography (NIL) processes this force is too small.
In order to overcome the disadvantages of passive wedge error compensation, active wedge error compensation is used. Active wedge error compensation first takes place in a manner equal to that of passive wedge error compensation. Instead of locking the relative position of the mask relative to the movable part of the wedge error compensating head or the substrate, measuring probes are used for referencing this relative position. Then, the movable part of the wedge error compensating head is placed onto three linear actuators arranged in the reference plane, e.g. at azimuthal intervals of 120°. By means of the measuring probes and by applying the linear actuators, it is possible to actively compensate for the wedge error. If piezo elements are used for the linear actuators, typically displacements of up to 80 μm can be compensated for. In this connection, the control displacement is the maximally available distance by which a linear actuator can move the movable part relative to the stationary part of the wedge error compensating head.
A problem related with this active wedge error compensation is the small control displacement, in particular if, e.g., piezo elements are used for the linear actuators. In a compact system, the available constructional space is limited. Therefore, the piezo elements cannot be elongated in order to increase the control displacement. The control displacements available for the actual imprinting stroke are reduced further if the maximally available control displacements are already necessary to a large extent for a tolerance compensation for the dimensions of the components used in the system, e.g. the chuck, the adapter frame, the mask holder, the substrate holder, etc. It can even be the case that only a few micrometers are left for the actual imprinting stroke.
In view of the above-mentioned problems of the prior art, it is an object of the present invention to provide a method and a device in which the control displacement available for the wedge error compensation is increased. It is a further object of the invention to be able to use the control displacement of the linear actuators almost completely for the imprinting stroke. These objects are achieved by the features of the claims.